The present invention relates to a method for manufacturing a crossbeam for stiffening an instrument panel of a motor vehicle, the crossbeam that is to be manufactured having at least two profiled portions, with cross sections differing from one another, arranged in axial prolongation.
The invention further concerns such a crossbeam.
A method of this kind, and such a crossbeam, are commonly known.
Crossbeams are used in the automotive industry in body design. As part of a motor vehicle body, the crossbeam is arranged so as to extend approximately horizontally in the region below the windshield between the so-called A-pillars. The purpose of the crossbeam is to strengthen the instrument panel. The crossbeam also has the task of stiffening the instrument panel, which is usually made of plastic or wooden parts. Mounts, to which the instrument panel (and also possibly a center console and the steering apparatus) are attached, are provided on the crossbeam.
Crossbeams for stiffening the instrument panel of a motor vehicle are usually manufactured with a profile cross section that is not uniform over the length of the crossbeam. In other words, crossbeams of this kind have at least two profiled portions, arranged in axial prolongation, which have profile cross sections that differ from one another. One of the profiled portions has a smaller cross section, while the other profiled portion possesses a larger cross section. For example, a crossbeam of this kind is configured so that it has one smaller-cross-section profiled portion in the form of a tubular profile, and one larger-cross-section profiled portion in the form of a box profile.
A change of this kind in the cross section or diameter of the crossbeam is necessary in order to shift the resonant frequency of the crossbeam in such a way as to prevent resonances of the crossbeam, and thus vibrations that may be transmitted in particular into the steering apparatus, over the entire speed range of the motor vehicle.
Another reason for manufacturing crossbeams of this kind with a non-constant cross section is that because of the wiring running in the instrument panel for the instruments, and the instruments themselves, the space available in the instrument panel is sometimes limited.
At present, crossbeams having profiled portions with different cross sections are manufactured by expanding the smaller-cross-section profiled portion, by internal high-pressure forming, to the cross section of the larger-cross-section profiled portion. Depending on the shape of the profiled portions, which can be different, a method of this kind, in which the smaller-cross-section profiled portion is expanded to the cross section of the larger-cross-section profiled portion, is very cost-intensive and sometimes also time-consuming.
Another kind of method for manufacturing a crossbeam of this kind consists in spanning the discontinuity in cross section between the profiled portion using drawn parts manufactured with the deep-drawing process, which are arranged in the longitudinal direction between the profiled portions that are spaced apart from one another in the longitudinal direction and are joined at the ends to the two profiled portions. The fabrication of drawn parts is also, however, time-consuming and cost-intensive.
It is usual in the development of motor vehicle bodies, in order to discover the crossbeam having the requisite properties that are suitable for the particular motor vehicle model by trying out different profile shapes, to perform test series in which a plurality of crossbeams with various profiles must be manufactured. The conventional method for manufacturing crossbeams is not suitable for such test series, however, because of its high cost and expenditure of time.
It is therefore the object of the invention to develop a method and a crossbeam of the kind cited initially in such a way that the crossbeam can be manufactured with little cost and little expenditure of time.
According to the present invention, this object is achieved, in terms of the method cited initially, in that the smaller-cross-section profiled portion is arranged so as to overlap the larger-cross-section profiled portion over at least a partial length, and that in the overlap region, the profiled portions are joined to one another in at least one direction perpendicular to the longitudinal direction by way of at least one rigid joining element.
This object is correspondingly achieved, in terms of the crossbeam cited initially, in that the smaller-cross-section profiled portion is arranged so as to overlap the larger-cross-section profiled portion over at least a partial length, and that in the overlap region, the profiled portions are joined to one another in at least one direction perpendicular to the longitudinal direction by way of at least one rigid joining element.
The method and the crossbeam according to the present invention differ from the known crossbeams, in which the discontinuity in cross section is spanned by forming methods, in that the two profiled portions of differing cross sections at least partially overlap one another, and are joined to one another in the overlap region by a rigid joining element. With this manufacturing method according to the present invention, it is advantageously possible to manufacture crossbeams in economical fashion from a wide variety of profile cross sections and profile shapes. With the procedure according to the present invention for joining the profiled portions to one another, any abrupt changes in profile cross sections can be spanned. The method according to the present invention is economical and time-saving, since it is possible to dispense with the manufacture of complex stamped or drawn parts. Because of the low cost and time expenditure, the method according to the present invention is particularly suitable for the manufacture of a plurality of crossbeams of different profile shapes in a test series. The manner according to the present invention of joining the profiled portions using at least one rigid joining element running in at least one direction perpendicular to the longitudinal direction makes it possible, despite the simplification of the manufacturing process and the simplification of the structure of the crossbeam, to advantageously avoid losses in the flexural stiffness of the crossbeam.
The object of the invention is thereby completely achieved.
In a preferred embodiment of the method, the smaller-cross-section profiled portion is introduced at least partially into the larger-cross-section profiled portion, and is then joined to the larger-cross-section profiled portion by way of the at least one joining element.
It is advantageous in this context that the crossbeam according to the present invention can continue to be as compact as possible in a direction perpendicular to the longitudinal direction of the crossbeam, since because the smaller-cross-section profiled portion penetrates into the larger-cross-section profiled portion, the larger-cross-section profiled portion determines the maximum extension of the crossbeam in a direction perpendicular to the longitudinal direction.
In a further preferred embodiment of the method, the profiled portions are made from steel, the profiled portions then being joined to one another by way of at least one joining element, in the form of a sheet piling, a web plate, or a profile element, that is directly joined to the profiled portions by welding, soldering, adhesive bonding, or the like.
In this situation in which the profiled portions are made from steel, the aforementioned joining elements can also be manufactured in particularly economical fashion from steel as geometrically simple elements, by cutting, bending, etc. The use of the same material for both the profiled portions and the joining element or elements has the advantage that the joining elements can be directly joined to the profiled portions by welding.
In a further preferred embodiment, the profiled portions are made from a lightweight metal, in particular aluminum or an aluminum or magnesium alloy, the profiled portions then being joined to one another by way of at least one joining element, in the form of an extruded profile, a sheet piling, a web plate, or a profile element, that is directly joined to the profiled portions by welding, soldering, adhesive bonding, or the like.
The method according to the present invention can advantageously also be used in the situation in which the crossbeam is produced by lightweight construction from lightweight metal, e.g. from aluminum, by the fact that the aluminum joining element or elements are also configured from aluminum, advantageously in the form of extruded profiles that can be manufactured economically and configured with suitable profile shapes, and that ensure a flexurally stiff join between the profiled portions.
In a further preferred embodiment, at least one slot, into which at least one joining element is inserted, is introduced into the larger-cross-section profiled portion and/or into the smaller-cross-section profiled portion.
It is advantageous in this context that the joining element that is arranged, in accordance with the above preferred configuration, partially in the cavity of the larger-cross-section profiled portion, can be welded in easily handled fashion to the larger-cross-section profiled portion, since the weld bead can be applied from outside in the region of the slot or slots.
In a further preferred embodiment of the crossbeam manufactured in this fashion, the smaller-cross-section profiled portion is a tubular profile, and the larger-cross-section profiled portion is a box profile with a rectangular, trapezoidal, triangular, or similar cross section.
As already mentioned, it is possible with the method according to the present invention to economically manufacture any desired crossbeams that have at least two profiled portions with different cross sections, i.e. with different cross-sectional shapes and/or different cross-sectional sizes. It is thus possible, at little cost and with equally little time expenditure, to manufacture a series of crossbeams for a test series in order to investigate the suitability and properties of different profile shapes.
In a further preferred embodiment of the crossbeam, at least one joining element is configured as a sleeve which has an opening through which the tubular profile is passed and whose outer contour is adapted to the inner contour of the box profile.
With this configuration of the joining element, it is particularly advantageous that the smaller-cross-section profiled portion, i.e. the tubular profile, experiences support on all sides in the larger-cross-section profiled portion, i.e. in the box profile, thus resulting in a particularly stable, flexurally stiff join between the two profiled portions.
In a further preferred embodiment of the crossbeam according to the present invention, at least one joining element is configured as a tubular profiled piece that is joined with one surface line to the tubular profile and joined with at least one further surface line to the box profile.
This configuration of the at least one joining element is particularly advantageous because the tubular profiled piece can be cut to length from the tubular profile that forms the smaller-cross-section profiled portion and that can be manufactured as cut goods, so that separate fabrication of joining elements can be entirely dispensed with. It is thereby possible to minimize cost in the manufacture of the cross,9beam. A flexurally stiff join between the two profiled portions is reliably achieved with this configuration of the joining element as well.
In a further particularly preferred embodiment of the method and of the crossbeam the larger-cross-section profiled portion is manufactured together with the at least one joining element in one piece in form of an extruded profile. In this case the one or plural joining elements are integral with the larger-cross-section profiled portion.
The particular advantage of this embodiment is that the manufacturing method is further simplified, because one method step is dispensed with, namely joining of the joining element or joining elements to the larger-cross-section profiled portion. On the other hand, the stability and mechanical resistance of the larger-cross-section profiled portion is improved, because predetermined breaking points like weldment joints are avoided.
Further advantages and features are evident from the description below and from the appended drawings.
It is understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention.